Overview

Stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. This can be due to ischemia (lack of blood supply) caused by thrombosis or embolism, or due to a hemorrhage.[1]

Stroke is a medical emergency and can cause permanent neurological damage, complications and death if not promptly diagnosed and treated. It is the third leading cause of death and the leading cause of adult disability in the United States and Europe. It is predicted that stroke will soon become the leading cause of death worldwide.[2]WHO defines stroke as, a neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours.

Classification

Transient ischemic attack

A transient ischemic attack is caused by the temporary disturbance of blood supply to a restricted area of the brain, resulting in brief neurologic dysfunction that usually persists for less than 24 hours.

In 2009, 34% of people hospitalized for stroke were younger than 65 years[44]

The incidence of stroke in people aged 18 to 50 years is estimated to be approximately 10%. [43]

The rate of decline in mortality rates of stroke in different age groups is as follows:[43]

Older then 65 years: from 534.1 to 245.2 per 100,000

45-65 years of age: from 43.5 to 20.2 per 100,000

18 to 44 years of age: from from 3.7 to 2.0 per 100,000

Gender

There is increased incidence of stroke in men as compared to women.

Race

The risk of incidence of first stroke is twice in African-American population as compared to Caucasians with increased mortality rates.[44]

Geographical distribution

There is increased incidence and mortality rates of stroke in developing countries as compared to developed countries due to low socioeconomic status and heath facilities.

In the USA, the highest death rates from stroke are in the southeastern United States.[44]

Diagnosis

Almost 10% of cerebrovascular events that present to the emergency department are not detected during evaluation.[46] This is more common when "presenting neurologic complaints are mild, nonspecific, or transient".[46]

Diagnosis is based on history of symptoms development, physical examination and imaging findings.

CT is very sensitive for identifying acute hemorrhage and is considered the gold standard.

Gradient echo and T2 susceptibility-weighted MRI are as sensitive as CT for detection of acute hemorrhage and are more sensitive for identification of prior hemorrhage.

MR diffusion weighted imaging is the most sensitive and specific test for diagnosing ischemic stroke and may help detect presence of infarction in few minutes of onset of symptoms. It may also help differentiate viable tissue from infarct area if combined with MR perfusion. For diagnosing ischemic stroke in the emergency setting, MRI scan has the sensitivity and specificity of 83% and 98% respectively.[47]

MRI scan is superior to CT scan for being more sensitive and specific in detection of lacunar and posterior fossa infarcts, differentiation between acute and chronic stroke and detection of microbleeds. Another additional advantage is absence of ionising radiation compared to CT scan. Some of the disadvantages of MRI scan may include lack of availability in acute setting, higher cost, inability to use it in patients with metallic implants. MRI with contrast cannot be used in patients with renal failure.[48][49]